With the advent of rotating machinery, high-speed rotors have been of interest to engineers. Rotating machinery has been employed in a wide range of applications in the past century. These applications range from steam turbines for electric power generation to the turbopumps used in the Space Shuttle Main Engines. As these machines have become more commonplace there has been an increased demand for lightweight, compact designs. The required power output of these units has also increased leading to ever high power to weight ratios. These leaner designs are the hallmark of the aerospace industry. Vibration problems, which occur more frequently in high power to weight machines, often lead to costly down time (and subsequent redesign) and, in some instances, catastrophic failure. A disproportionate number of vibration problems in rotating machinery can be attributed to highly preswirled fluid entering tight clearance locations such as seals and fluid bearings. The relationship between high fluid pre-swirl and undesirable vibration issues is clear. Machines with high levels of fluid pre-swirl are more susceptible to instabilities and vibration problems. A top priority in rotordynamic design, therefore, is to develop devices to minimize the level of fluid pre-swirl entering tight clearance locations. The reverse vortex ring has been found to not only minimize this detrimental pre-swirl but to actually reverse the direction of the swirl. A characteristic that historically has been detrimental to rotating machinery has now become an asset to ameliorate vibration issues through the use of the reverse vortex ring (RVR).
It is an objective of the present invention to provide an apparatus for reducing vibration in high-speed rotating machinery induced by pre-swirled fluid entering tight clearance locations such as seals and fluid bearings. It is a further objective to provide an apparatus that involves a minimum of modifications to existing machinery designs. It is a still further objective of the invention to minimize the number, complexity and weight of any parts that must be added to reduce such vibrations. It is yet a further objective to provide an apparatus that is durable and simple to manufacture. Finally, it is an objective of the present invention to provide an apparatus that may be scaled to a wide variety of applications and that will function efficiently with a wide variety of fluids in varying conditions of temperature, pressure and other conditions.
While some of the objectives of the present invention are disclosed in the prior art, none of the inventions found include all of the requirements identified.